Law enforcement officials tell NPR that as they watched suspect Jimmy Lee Dykes, thanks to a hidden camera they were able to get into the bunker, his demeanor seemed to change over the weekend and into Monday.

During the first few days of the standoff, which began when Dykes killed a school bus driver and snatched Ethan one week ago, the gunman could be seen attending to the boy's needs and he seemed to be able to sleep peacefully. But later, Dykes was showing signs of agitation and ignoring the child, officials say. He was also seen holding a gun. Authorities were worried that the stress might lead Dykes to harm the boy.

As the standoff went on, teams worked up a rescue plan and practiced in a mock up of the bunker. Then Monday afternoon, they acted.

Update at 9:18 p.m. ET. Firefight At Scene

We now learn that the hostage-taker engaged in a firefight with SWAT agents who stormed his underground bunker Monday in an attempt to rescue his 5-year-old hostage.

Here's more from The Associated Press:

"Also, bomb technicians scouring the property found two explosive devices, one in the bunker, the other in a plastic pipe negotiators used to communicate with the man."

A law enforcement official told the news agency that officers killed 65-year-old Jimmy Lee Dykes on Monday.

Ethan, the 5-year-old hostage, appeared to be normal a day after his ordeal ended.

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"We know he's OK physically, but we don't know how he is mentally," Betty Jean Ransbottom, the boy's grandmother, told the AP on Tuesday.

Our original post continues:

ABC News is reporting that "officials were able to insert a high-tech camera into the 6-by-8-foot bunker to monitor [kidnapper Jimmy Lee] Dykes' movements, and they became increasingly concerned that he might act out," according to "a law enforcement source with direct knowledge' of the situation.

Also, "the FBI had created a mock bunker near the site and had been using it to train agents for different scenarios to get Ethan out, sources told ABC News."

"FBI officers had lowered a camera into the bunker — they would not reveal how, saying they may want to use the method in the future — which allowed them to determine when to throw in the flash-bang to distract Dykes.That's when they entered through a door at the top of the bunker."

According to AL.com, "neighbor Micah Senn, 16, who lives a few hundred yards from the hostage site, said he heard the explosion followed by four to five rounds of gunfire. 'I knew something had to have happened,' he said."

CNN looks at one of the other questions arising out of this story — how will the trauma of seeing his bus driver murdered and then being held in a small underground bunker for nearly a week with a gunman affect little Ethan?

"It's very hard to tell how he's going to do," Louis Krouse, a psychiatrist at Chicago's Rush Medical Center tells CNN. "On the one hand, he might get right back to his routine and do absolutely fine. But on the other hand, the anxieties, the trauma, what we call an acute stress disorder even post traumatic stress symptoms can occur."

The good news, as we reported Monday night, is that FBI special agent Stephen Richardson said Ethan was "laughing, joking, playing, eating, things you'd expect a normal 5-to-6-year-old young man to do."

Ethan was rescued, by the way, two days before his sixth birthday, according to Dan Carsen of NPR member station WBHM.

As for the 65-year-old Dykes, the local Dothan Eagle writes that neighbors say he "changed over time," from a friendly man to one who threatened "anyone who touched his property."